[3] In 1945, Mansfield married Rawland F. "Rollie" Smith,[4][5][6] a Navy veteran who would become a McDonald's franchisee, eventually owning three stores in Rapid City, South Dakota.

[7] Mansfield met McDonald's Corp. founder Ray Kroc, who was 26 years her senior, while playing the organ at the Criterion Restaurant in St. Paul, Minnesota in 1957.

She later bequeathed an additional $1.6 billion to open Salvation Army Kroc Centers across the nation, the largest one-time gift ever recorded.

She anonymously gifted a Paul Conrad sculpture depicting a nuclear mushroom cloud, Chain Reaction, to the city of Santa Monica, where it still sits today.

[20] Her will included significant bequests for a number of organizations: The biography Ray & Joan: The Man Who Made The McDonald's Fortune and The Woman Who Gave it All Away, published by Dutton in 2016, and written by Lisa Napoli, examines the Krocs' relationship.